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  <title>Immersive Session with hands</title>
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<body>
  <header>
    <details open>
      <summary>Immersive VR Session with hands</summary>
      <p>
        This sample demonstrates a simple VR session that shows the user's hands.
        If your device supports this feature, you will see your hands using a set
        of cubes. Each cube represents a joint in your hand.
        <a class="back" href="./">Back</a>
      </p>
    </details>
  </header>
  <main style='text-align: center;'>
    <p>Click 'Enter XR' to see content</p>
  </main>
  <script type="module">
    import { WebXRButton } from './js/util/webxr-button.js';
    import { Scene } from './js/render/scenes/scene.js';
    import { Node } from './js/render/core/node.js';
    import { Renderer, createWebGLContext } from './js/render/core/renderer.js';
    import { Gltf2Node } from './js/render/nodes/gltf2.js';
    import { SkyboxNode } from './js/render/nodes/skybox.js';
    import { BoxBuilder } from './js/render/geometry/box-builder.js';
    import { PbrMaterial } from './js/render/materials/pbr.js';
    import { QueryArgs } from './js/util/query-args.js';
    import {mat4} from './js/render/math/gl-matrix.js';
    import {vec3} from './js/render/math/gl-matrix.js';
    import {Ray} from './js/render/math/ray.js';

    // This library matches XRInputSource profiles to available controller models for us.
    import { fetchProfile } from 'https://cdn.jsdelivr.net/npm/@webxr-input-profiles/motion-controllers@1.0/dist/motion-controllers.module.js';

    // The path of the CDN the sample will fetch controller models from.
    const DEFAULT_PROFILES_PATH = 'https://cdn.jsdelivr.net/npm/@webxr-input-profiles/assets@1.0/dist/profiles';

    // XR globals.
    let xrButton = null;
    let xrRefSpace = null;
    let isAR = false;
    let radii = new Float32Array(25);
    let positions = new Float32Array(16*25);
    
    // Boxes
    let boxes_left = [];
    let boxes_right = [];
    let boxes_none = [];
    let tracked_boxes_left = [];
    let tracked_boxes_right = [];
    let tracked_boxes_none = [];
    let boxes = { input_left: boxes_left, input_right: boxes_right, input_none: boxes_none, tracked_left: tracked_boxes_left, tracked_right: tracked_boxes_right, tracked_none: tracked_boxes_none };
    let indexFingerBoxes = { input_left: null, input_right: null, tracked_left: null, tracked_right: null };
    const defaultBoxColor = {r: 0.5, g: 0.5, b: 0.5};
    const leftBoxColor = {r: 1, g: 0, b: 1};
    const rightBoxColor = {r: 0, g: 1, b: 1};
    let interactionBox = null;
    let leftInteractionBox = null;
    let rightInteractionBox = null;

    // WebGL scene globals.
    let gl = null;
    let renderer = null;
    let scene = new Scene();
    scene.addNode(new Gltf2Node({ url: './media/gltf/space/space.gltf' }));
    scene.addNode(new SkyboxNode({ url: './media/textures/milky-way-4k.png' }));
    
    function createBoxPrimitive(r, g, b) {	
      let boxBuilder = new BoxBuilder();	
      boxBuilder.pushCube([0, 0, 0], 1);	
      let boxPrimitive = boxBuilder.finishPrimitive(renderer);	
      let boxMaterial = new PbrMaterial();	
      boxMaterial.baseColorFactor.value = [r, g, b, 1];	
      return renderer.createRenderPrimitive(boxPrimitive, boxMaterial);	
    }

    function addBox(x, y, z, r, g, b, offset) {
      let boxRenderPrimitive = createBoxPrimitive(r, g, b);
      let boxNode = new Node();
      boxNode.addRenderPrimitive(boxRenderPrimitive);
      // Marks the node as one that needs to be checked when hit testing.
      boxNode.selectable = true;
      return boxNode;
    }

    function initHands() {
      for (const box of boxes_left) {
        scene.removeNode(box);
      }
      for (const box of boxes_right) {
        scene.removeNode(box);
      }
      boxes_left = [];
      boxes_right = [];
      boxes = { input_left: boxes_left, input_right: boxes_right, input_none: boxes_none, tracked_left: tracked_boxes_left, tracked_right: tracked_boxes_right, tracked_none: tracked_boxes_none };
      if (typeof XRHand !== 'undefined') {
        for (let i = 0; i <= 24; i++) {
          const r = .6 + Math.random() * .4;
          const g = .6 + Math.random() * .4;
          const b = .6 + Math.random() * .4;
          boxes_left.push(addBox(0, 0, 0, r, g, b));
          boxes_right.push(addBox(0, 0, 0, r, g, b));
          tracked_boxes_left.push(addBox(0, 0, 0, r, g, b));
          tracked_boxes_right.push(addBox(0, 0, 0, r, g, b));
        }
      }
      if (indexFingerBoxes.input_left) {
        scene.removeNode(indexFingerBoxes.left);
      }
      if (indexFingerBoxes.input_right) {
        scene.removeNode(indexFingerBoxes.input_right);
      }
      if (indexFingerBoxes.tracked_left) {
        scene.removeNode(indexFingerBoxes.tracked_left);
      }
      if (indexFingerBoxes.tracked_right) {
        scene.removeNode(indexFingerBoxes.tracked_right);
      }
      indexFingerBoxes.input_left = addBox(0, 0, 0, leftBoxColor.r, leftBoxColor.g, leftBoxColor.b);
      indexFingerBoxes.input_right = addBox(0, 0, 0, rightBoxColor.r, rightBoxColor.g, rightBoxColor.b);
      indexFingerBoxes.tracked_left = addBox(0, 0, 0, leftBoxColor.r, leftBoxColor.g, leftBoxColor.b);
      indexFingerBoxes.tracked_right = addBox(0, 0, 0, rightBoxColor.r, rightBoxColor.g, rightBoxColor.b);
    }

    // Checks to see if WebXR is available and, if so, queries a list of
    // XRDevices that are connected to the system.
    function initXR() {
      // Adds a helper button to the page that indicates if any XRDevices are
      // available and let's the user pick between them if there's multiple.
      xrButton = new WebXRButton({
        onRequestSession: onRequestSession,
        onEndSession: onEndSession
      });
      document.querySelector('header').appendChild(xrButton.domElement);

      // Is WebXR available on this UA?
      if (navigator.xr) {
        // If the device allows creation of exclusive sessions set it as the
        // target of the 'Enter XR' button.
        navigator.xr.isSessionSupported('immersive-vr').then((supported) => {
          if (supported)
            xrButton.enabled = supported;
          else
            navigator.xr.isSessionSupported('immersive-ar').then((supported) => {
              isAR = true;
              xrButton.enabled = supported;
            });
        });
      }
    }

    // Called when the user selects a device to present to. In response we
    // will request an exclusive session from that device.
    function onRequestSession() {
      return navigator.xr.requestSession(isAR?'immersive-ar':'immersive-vr', { optionalFeatures: ['local-floor', 'bounded-floor', 'hand-tracking'] }).then(onSessionStarted);
    }

    // Called when we've successfully acquired a XRSession. In response we
    // will set up the necessary session state and kick off the frame loop.
    function onSessionStarted(session) {
      // This informs the 'Enter XR' button that the session has started and
      // that it should display 'Exit XR' instead.
      xrButton.setSession(session);

      // Listen for the sessions 'end' event so we can respond if the user
      // or UA ends the session for any reason.
      session.addEventListener('end', onSessionEnded);
      session.addEventListener('inputsourceschange', onInputSourcesChange);
      // trackedSources are still experimental. Don't rely on this feature yet.
      session.addEventListener('trackedsourceschange', onInputSourcesChange);

      session.addEventListener('visibilitychange', e => {
        // remove hand controller while blurred
        if(e.session.visibilityState === 'visible-blurred') {
          for (const box of boxes['input_left']) {
            scene.removeNode(box);
          }
          for (const box of boxes['input_right']) {
            scene.removeNode(box);
          }
          for (const box of boxes['tracked_left']) {
            scene.removeNode(box);
          }
          for (const box of boxes['tracked_right']) {
            scene.removeNode(box);
          }
        }
      });

      // Create a WebGL context to render with, initialized to be compatible
      // with the XRDisplay we're presenting to.
      gl = createWebGLContext({
        xrCompatible: true
      });

      // Create a renderer with that GL context (this is just for the samples
      // framework and has nothing to do with WebXR specifically.)
      renderer = new Renderer(gl);

      initHands();

      // Set the scene's renderer, which creates the necessary GPU resources.
      scene.setRenderer(renderer);

      // Use the new WebGL context to create a XRWebGLLayer and set it as the
      // sessions baseLayer. This allows any content rendered to the layer to
      // be displayed on the XRDevice.
      session.updateRenderState({ baseLayer: new XRWebGLLayer(session, gl) });

      // Get a frame of reference, which is required for querying poses. In
      // this case an 'local' frame of reference means that all poses will
      // be relative to the location where the XRDevice was first detected.
      session.requestReferenceSpace('local').then((refSpace) => {
        xrRefSpace = refSpace.getOffsetReferenceSpace(new XRRigidTransform({ x: 0, y: 0, z: 0 }));

        // Inform the session that we're ready to begin drawing.
        session.requestAnimationFrame(onXRFrame);
      });
    }

    // Called when the user clicks the 'Exit XR' button. In response we end
    // the session.
    function onEndSession(session) {
      session.end();
    }

    // Called either when the user has explicitly ended the session (like in
    // onEndSession()) or when the UA has ended the session for any reason.
    // At this point the session object is no longer usable and should be
    // discarded.
    function onSessionEnded(event) {
      xrButton.setSession(null);

      // In this simple case discard the WebGL context too, since we're not
      // rendering anything else to the screen with it.
      renderer = null;
    }

    function onInputSourcesChange(event) {
      onSourcesChange(event, "input_");
    }

    function onTrackedSourcesChange(event) {
      onSourcesChange(event, "tracked_");
    }

    function onSourcesChange(event, type) {
        // As input sources are connected if they are tracked-pointer devices
        // look up which meshes should be associated with their profile and
        // load as the controller model for that hand.
        for (let inputSource of event.added) {
          if (inputSource.targetRayMode == 'tracked-pointer') {
            // Use the fetchProfile method from the motionControllers library
            // to find the appropriate glTF mesh path for this controller.
            fetchProfile(inputSource, DEFAULT_PROFILES_PATH).then(({profile, assetPath}) => {
              // Typically if you wanted to animate the controllers in response
              // to device inputs you'd create a new MotionController() instance
              // here to handle the animation, but this sample will skip that
              // and only display a static mesh for simplicity.

              scene.inputRenderer.setControllerMesh(new Gltf2Node({url: assetPath}), inputSource.handedness, inputSource.profiles[0]);
            });
          }
        }
      }

    function updateInputSources(session, frame, refSpace) {
      updateSources(session, frame, refSpace, session.inputSources, "input_");
    }

    function updateTrackedSources(session, frame, refSpace) {
      // session.trackedSources are still experimental. Don't rely on this feature yet.
      if (session.trackedSources) {
        updateSources(session, frame, refSpace, session.trackedSources, "tracked_");
      }
    }

    function updateSources(session, frame, refSpace, sources, type) {
      if(session.visibilityState === 'visible-blurred') {
        return;
      }
      for (let inputSource of sources) {
        let hand_type = type + inputSource.handedness;
        if (type == "input_") {
          let targetRayPose = frame.getPose(inputSource.targetRaySpace, refSpace);
          if (targetRayPose) {
            if (inputSource.targetRayMode == 'tracked-pointer') {
              scene.inputRenderer.addLaserPointer(targetRayPose.transform);
            }

            let targetRay = new Ray(targetRayPose.transform);
            let cursorDistance = 2.0;
            let cursorPos = vec3.fromValues(
                targetRay.origin.x,
                targetRay.origin.y,
                targetRay.origin.z
                );
            vec3.add(cursorPos, cursorPos, [
                targetRay.direction.x * cursorDistance,
                targetRay.direction.y * cursorDistance,
                targetRay.direction.z * cursorDistance,
                ]);

            scene.inputRenderer.addCursor(cursorPos);
          }
        }

        if (!inputSource.hand && inputSource.gripSpace) {
          let gripPose = frame.getPose(inputSource.gripSpace, refSpace);
          if (gripPose) {
            scene.inputRenderer.addController(gripPose.transform.matrix, inputSource.handedness, inputSource.profiles[0]);
          } else {
            scene.inputRenderer.hideController(hand_type);
          }
        }

        let offset = 0;
        if (!inputSource.hand) {
          for (const box of boxes[hand_type]) {
            scene.removeNode(box);
          }
          scene.removeNode(indexFingerBoxes[hand_type]);

          continue;
        } else {
          let pose = frame.getPose(inputSource.targetRaySpace, refSpace);
          if (pose === undefined) {
            console.log("no pose");
          }

          if (!frame.fillJointRadii(inputSource.hand.values(), radii)) {
            console.log("no fillJointRadii");
            continue;
          }
          if (!frame.fillPoses(inputSource.hand.values(), refSpace, positions)) {
            console.log("no fillPoses");
            continue;
          }
          for (const box of boxes[hand_type]) {
            scene.addNode(box);
            let matrix = positions.slice(offset * 16, (offset + 1) * 16);
            let jointRadius = radii[offset];
            offset++;
            mat4.getTranslation(box.translation, matrix);
            mat4.getRotation(box.rotation, matrix);
            box.scale = [jointRadius, jointRadius, jointRadius];
          }
          	
          // Render a special box for each index finger on each hand	
          const indexFingerBox = indexFingerBoxes[hand_type];
          scene.addNode(indexFingerBox);	
          let joint = inputSource.hand.get('index-finger-tip');	
          let jointPose = frame.getJointPose(joint, xrRefSpace);	
          if (jointPose) {	
            let matrix = jointPose.transform.matrix;
            mat4.getTranslation(indexFingerBox.translation, matrix);
            mat4.getRotation(indexFingerBox.rotation, matrix);
            indexFingerBox.scale = [0.02, 0.02, 0.02];	
          }
        }
      }
    }
    
    function UpdateInteractables(time) {
      // Add scene objects if not present
      if (!interactionBox) {	
        // Add box to demonstrate hand interaction
        function AddInteractionBox(r, g, b) {	
          let box = new Node();	
          box.addRenderPrimitive(createBoxPrimitive(r, g, b));	
          box.translation = [0, 0, -0.65];	
          box.scale = [0.25, 0.25, 0.25];	
          return box;	
        }	
        interactionBox = AddInteractionBox(defaultBoxColor.r, defaultBoxColor.g, defaultBoxColor.b);	
        leftInteractionBox = AddInteractionBox(leftBoxColor.r, leftBoxColor.g, leftBoxColor.b);	
        rightInteractionBox = AddInteractionBox(rightBoxColor.r, rightBoxColor.g, rightBoxColor.b);	
        scene.addNode(interactionBox);	
        scene.addNode(leftInteractionBox);	
        scene.addNode(rightInteractionBox);	
      }
      
      function Distance(nodeA, nodeB) {	
        return Math.sqrt(	
          Math.pow(nodeA.translation[0] - nodeB.translation[0], 2) +	
          Math.pow(nodeA.translation[1] - nodeB.translation[1], 2) +	
          Math.pow(nodeA.translation[2] - nodeB.translation[2], 2));	
      }

      // Perform distance check on interactable elements
      const interactionDistance = interactionBox.scale[0];	
      leftInteractionBox.visible = false;	
      rightInteractionBox.visible = false;	
      if (Distance(indexFingerBoxes.input_left, interactionBox) < interactionDistance) {
        leftInteractionBox.visible = true;	
      } else if (Distance(indexFingerBoxes.input_right, interactionBox) < interactionDistance) {
        rightInteractionBox.visible = true;	
      }	
      interactionBox.visible = !(leftInteractionBox.visible || rightInteractionBox.visible);
      
      mat4.rotateX(interactionBox.matrix, interactionBox.matrix, time/1000);
      mat4.rotateY(interactionBox.matrix, interactionBox.matrix, time/1500);
      leftInteractionBox.matrix = interactionBox.matrix;
      rightInteractionBox.matrix = interactionBox.matrix;
    }

    // Called every time the XRSession requests that a new frame be drawn.
    function onXRFrame(t, frame) {
      let session = frame.session;

      // Per-frame scene setup. Nothing WebXR specific here.
      scene.startFrame();

      // Inform the session that we're ready for the next frame.
      session.requestAnimationFrame(onXRFrame);

      updateInputSources(session, frame, xrRefSpace);
      updateTrackedSources(session, frame, xrRefSpace);
      UpdateInteractables(t);

      // Get the XRDevice pose relative to the Frame of Reference we created
      // earlier.
      let pose = frame.getViewerPose(xrRefSpace);

      // Getting the pose may fail if, for example, tracking is lost. So we
      // have to check to make sure that we got a valid pose before attempting
      // to render with it. If not in this case we'll just leave the
      // framebuffer cleared, so tracking loss means the scene will simply
      // disappear.
      if (pose) {
        let glLayer = session.renderState.baseLayer;

        // If we do have a valid pose, bind the WebGL layer's framebuffer,
        // which is where any content to be displayed on the XRDevice must be
        // rendered.
        gl.bindFramebuffer(gl.FRAMEBUFFER, glLayer.framebuffer);

        // Clear the framebuffer
        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

        // Loop through each of the views reported by the frame and draw them
        // into the corresponding viewport.
        for (let view of pose.views) {
          let viewport = glLayer.getViewport(view);
          gl.viewport(viewport.x, viewport.y,
            viewport.width, viewport.height);

          // Draw this view of the scene. What happens in this function really
          // isn't all that important. What is important is that it renders
          // into the XRWebGLLayer's framebuffer, using the viewport into that
          // framebuffer reported by the current view, and using the
          // projection matrix and view transform from the current view.
          // We bound the framebuffer and viewport up above, and are passing
          // in the appropriate matrices here to be used when rendering.
          scene.draw(view.projectionMatrix, view.transform);
        }
      } else {
        // There's several options for handling cases where no pose is given.
        // The simplest, which these samples opt for, is to simply not draw
        // anything. That way the device will continue to show the last frame
        // drawn, possibly even with reprojection. Alternately you could
        // re-draw the scene again with the last known good pose (which is now
        // likely to be wrong), clear to black, or draw a head-locked message
        // for the user indicating that they should try to get back to an area
        // with better tracking. In all cases it's possible that the device
        // may override what is drawn here to show the user it's own error
        // message, so it should not be anything critical to the application's
        // use.
      }

      // Per-frame scene teardown. Nothing WebXR specific here.
      scene.endFrame();
    }

    // Start the XR application.
    initXR();
  </script>
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